The present invention relates to an aircraft or airborne vehicle with foldable and/or pivotable wings under utilization of a resilient device for automatic deployment of the wing.
Aircraft or vehicles of the type to which the invention pertains are, for example, disclosed in U.S. Pat. No. 4,410,151. These vehicles are also known as drones and are launched by means of a booster rocket from a suitable silo or container. In order to store the craft in such a container, its wings must be amenable to be folded in some fashion because the vehicle as a whole is to be fairly tightly stored within the container being configured that indeed a rocket launch can be taken place from it.
For such vehicles, it is quite desirable to launch them in a completely automated fashion without requiring any preparation just immediately prior to the takeoff. This of course means that the wings can be deployed only after the vehicle has left the silo or container, but still during the phase of rocket assisted or booster flight. However, this booster phase is of a very short duration, and may last just barely a second so that the deployment of the wings may require particularly large adjustment forces. The deployment operation, however, is interfered with by the inertia of the accelerating vehicle, and by the immediately effective air resistance. Generally speaking then, one needs a very significant amount of energy for the fast deployment operation under utilization of the mass of the objects, and stoppage of the deployment movement when the deployment is completed is a rapid one indeed. Thus, deployment produces temporarily high kinetic energy of the deployment process itself which has to be absorbed in some fashion prior to completion of the deployment in order to avoid damage.
The aforementioned U.S. Pat. No. 4,410,151 suggests regular springs as a propelling mechanism for the deployment of wings or wing portions. In view of the limited space available, the lever action for obtaining, for example, a turning motion or pivot motion, or both, of the wing is very short. Thus, the forces necessary for wing deployment are significant and approach the permissible limits which the material can take up; since marginal conditions are undesirable, the duration of rocket boosting may have to be extended, which is undesirable for many reasons, or even impossible. Alternatively, the requisite forces under utilization of a short lever arm permits only to generate torques which are just sufficient to overcome interfering moments resulting, for example, from aerodynamic forces setting up interfering moments. Such deployment mechanism would still be unsatisfactory because they act too slow. Also, it may require an interlocking of the motion for the two wings such that they deploy in a strictly symmetrical and, therefore. balanced fashion. All this adds to the weight, and since these drones are small and light, any additional weight is highly undesirable. Also, fuel would have to be increased, which is to be maintained in the vicinity of the center of gravity.